Telephone toll-circuits



0. M. ARNOLD AND J. F. TOOMEY.

TELEPHONE TOLL CIRCUITS. APPLICATION FILED FEB. 24, 1919.

1,376,391 Patented May 3, 1921.

OPERA TIN? INVENTORS A ITTORNEY UNITED STATES PATENT OFFICE.

OSCAR M. ARNOLD AND JOHN F. TOOMEY, OF NEW YORK, N. Y., ASSIGNORS TO AMERI- CAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEPHONE TOLL-CIRCUITS.

Specification of Letters Patent.

Patented May 3, 1921.

Application filed February 24, 1919. Serial No. 278,948.

To all whom it may concern:

Be it known that we, OSCAR M. ARNOLD and JOHN F. TooMEY, residing at New York, in the counties of Bronx and New York, and State of New York, have invented certain Improvements in Telephone Toll-Circuits, of which the following is a specification.

This invention relates to telephone apparatus and circuits for use in connection with telephone toll systems at private branch exchanges.

It is sometimes desirable to provide private toll lines terminating at private branch exchanges, and as these lines are not always sufficient in number to occupy an attendants entire attention, it is customary to also provide in addition a certain number of local lines. To obtain the full advantage of improved transmission over toll lines, it is desirable that the private branch exchange operator be provided with toll cord circuits for use in connection with toll calls, and with local cord circuits for use only in connection with local calls. One of the principal objects of this invention is the provision of means whereby cords of the former type may be used for toll service, while cords of the latter type cannot be used therefor. Another object consists in the provision of an improved toll line and cord circuit for cooperation with said toll line. Other and further objects of the invention will hereinafter appear.

The objects of this invention are obtained by providing means in connection with the toll trunks whereby the transmission circuit of the trunk is only rendered operative when one of the toll cord circuits, above referred to, is associated therewith. The transmission circuit remains inoperative when on of the cords employed for handling local trunks is associated therewith.

In the accompanying drawing, one embodiment of this invention is diagrammatically represented.

At A a toll line is shown, and at B and C toll and local cord circuits are respectively illustrated, the cord circuit B being adapted for completing toll calls, and the cord circuit C being adapted for completing local connections over local lines such as D. E represents a private branch exchange operators equipment, which may be interchangeably connected with either of the cords B or C.

The details of this apparatus may be sufficiently understood from a description of the operation. It will be assumed that a distant toll operator desires connection with the illustrated private branch exchange over trunk A. The distant toll operator therefore transmits ringing current over talking conductors 1 and 2 of trunk A, thereby energlzing ringing relay 3, in a well known manner, which in turn operates relay 4; by a circuit from the grounded battery, armature and contact of relay 3, winding of relay 4, left hand contact and armature of relay 13 to ground. Relay 4 is looked over its left hand front contact, and at its right hand front contact completes a circuit for line lamp 5. The operator, upon answering said incoming call, associates plug P of cord B with jack J of the trunk, and establishes a circuit from ground, high resistance winding of busy test relay 6, conductor 7, tip contacts of plug P and jack J, talking conductor 1, conductor 8, upper contact and armature of relay 9, conductor 10. windings of relays 11 and 12 to grounded battery. The high resistance winding of relay 6 prevents the operation of marginal relay 12, but relay 11 will be energized by the previously traced circuit.

The operation of relay 11 provides a path for current which energizes relay 13 as follows: grounded battery, left hand armature and contact of relay 12, left hand winding of relay 13, over closed armature and contact of relay 11, conductor 16, talking conductor 2, ring contacts of jack J and plug P,

conductor of cord B, armature'and contact of relay 17 to ground at 18. Upon the energization of relay 13 its left hand armature will be attracted, opening its contact at 19, breaking the path for current, previ ously described in connection with the looking circuit for relay 4, and retiring line lamp 5 of the trunk. The operation of relay 13 also serves to energize relay 9 by a circuit which may be traced from ground, left hand armature of relay 13. conductor 20, winding of relay 9 to grounded battery. Relay 9 will attract its armatures, breaking the circuits previously described in connection with the ringing relay 3, and also relays 11 and 12. The energization of relay 9 will also furnish a talking circuit by way of the conductors 1 and 2 of the trunk. In the meantime relay 13 at its right hand front v tacts of plug P contact has completed a circuit from ground, right hand armature and contact of relay 12, right hand winding, armature and contact of said relay 13, over sleeve contacts of jack J and plug P, relay 17 to grounded battery, thus energizing relay 17 which will attract its upper armatures, dissociating said armatures from their contacts with conductor 7 and ground 18, and providing a talking circuit over conductors 21 and 22 of cord B. The operator upon manipulating key K of the toll cord B is enabled to conversewith the distant operator over talking conductors l and 2 of trunk A. Having obtained the number desired from the dis taint operator, she may complete the connection over the cord B at the private branch exchange by associating plug P with the jack of a wanted line in a manner which will presently be described. 7

The operation of relay 17, in addition to attracting its upper arinatures, previously outlined, will also attract its lower armature, closing a circuit which will operate relay 23 from grounded battery, contact 24; of lrcy K, conductor 25, lower armature of relay 17, winding of relay 23, conductor 26, armature and contact of relay 27 to ground. The re lay 23 upon operation will attract its arinature, breaking contact 28 preventing the operation of relay 29, and holding open the circuit for lanip 30 w iich will not be lighted at this time.

Should the distant operator wish to again ring or signal the private branch exchange operator at this period, however, ringing current will be sent from the distant end yer conductor 1 of toll trunk A, tip conacts oi jaclr J and plug P, conductor 2i of the toll cord 13 to point 31, upper left winding of repeating coil 3., conductor 32, through windings of relay 27, conductor 33, lower left winding of repeating coil conductor back over conductor 22, conand jaclr Cl, and conductor 2 of trunk line A. ilelay 27 will be operated by the circuit just described, and upon attracting its armature will l th ground connecyi n thereat. The c uit governing the energization of relay will true be broken, and a current path will be furnished for relay 29 and lamp 30 from grounded battery, contact 2% of lrey K, conductor 25, contact and armature oi relay l7, conductor 35, through said lamp, winding of relay 29 and armature of relay 23 to ground. lilelay 29 is slow operating and upon being energized completes over its upper armature and contact a looking for its own winding in series with lamp The operator, in re sponse to the lamp signal 30, will connect her head set to the talking circuit by manipulating lrey K. The operation of key K will breakcontact 24, and lamp 30 will be retired in an obvious manner.

The plug P is adapted to be operatively associated with either a local circuit or a toll line. In case the call incoming over toll line ll, previously referred to, is for connection with another toll line, the operator, upon associating plug P with an outgoing toll trunk similar to trunlr A, which will be used for the purpose of description, cornpletes path for current from ground,

through high resistance relay 6, conductor.

a current path from grounded battery, left 1 hand armature and contact of relay 12, left hand winding of relay l3, armature and contact of relay 11, conductor 16, talking conductor 2, ring contacts of jack J and plug P armature and contact 36 of relay 37, conductor 38, upper winding of relay 39, to ground. Relay 39 is also operated by this circuit and completes a circuit over its upper armature and ground, conductor 1), winding of relay ll, to grounded battery. Relay ell is energized by this circuit and attracts its armature, breaking contacts l2 and 43 and connecting the tip and ring conductors to talking conductors 21 and 22, eliminating repeating coil R from the circuit and providing a direct connection over the talking conductors of the cord, as will presently appear.

Upon the attraction of lower armature of relay 39, a circuit which would otherwise provide current forlainp 49 will be broken at contact 45. This lamp does not glow when the toll cord B is connected with a toll line and functions only when said cord is connected with a local line. The relay open. atesin conjunction with relay 13 in trunk A to provide a circuit from ground, right hand .arinature oi relay 12, right hand winding,

armature and contact of relay 13, sleeve contacts oi jack J and plug P sleeve conductor 44 of cord 13, armature and lower winding of relay 39 to grounded battery. Relays 39 and 13, are locked over the circuit just traced. Current is also furnished to the operation of relay do, over a path which may be traced as follows: from sleeve conductor 441-, over conductor 47, winding of relay 46 to grounded battery. The energizetion of relay 46 causes relay 37 to operate over a path for current from ground, armature of relay 4:6, conductorA-S, winding of relay 37 to grounder battery. Relay 37 in operating attracts its upper armatures, connects the tip and ring conductors of plug P to talking conductors 21 and 22 over the armatures of relay 41, which as previously described, are attracted by the energization of said relay 41. As the plug P is connected, as formerly indicated, with an incoming toll trunk, a talking circuit is now established from said incoming trunk over toll cord B to an outgoing trunk. A bridge through the ringing responsive relay 27 is associated with said talking circuit, but as this bridge is of high impedance a high grade of transmission is assured.

If in response to an incoming call over toll line A, indicated by the lighting of lamp 5, the private branch exchange operator upon associating plug P with jack J and manipulating key K, should find that a local connection is desired, she would connect the plug P with the jack of the wanted local line. such as is shown at D. Upon the association of the plug P with jack J a current path would be furnished from ground, through cut-off relay 54, sleeve contacts of jack J and plug P over the sleeve conductor 44, conductor 47, winding of relay 46 to grounded battery. This circuit will energize relay 54 causing it to attract its armatures and cut off the windings of line relay 58 so that line lamp 57 will be prevented from operating. This circuit will also cause relay 46 of cord B to operate and attract its armature. This operation will in turn provide for the energization of relay 37 by a circuit from ground, armature and contact of relay 46 through winding of relay 37 to grounded battery. The energization of relay 37 causes it to attract its upper armatures, thereby connecting said armatures to the tip and ring conductors of cord B. When plug P is-associated with a local line, switching relay 39 will not operate, due to the fact that the sleeve'conductors of plug P and jack J make contact first and operate relay 54, which, in turn, disconnects the windings of relay 58 from the talking conductors before the ring conductors of plug P and jack J make contact. Thus battery will be removed from the ring conductor of the line before the winding of relay 39 is connected. As relay 39 controls the circuit by which relay 41 is energized the latter relay will likewise not be operated. Repeating coil R of cord B will therefore be included in the talking circuit. Battery is supplied as in the usual common battery cord as will presently appear. A talking circuit will therefore be completed from the tip ant. ring conductors previously indicated, over contacts 42 and 43, through repeating coil B- to conductors 21 and 22. As relay 17 connected to the sleeve of plug P has been energized and has attracted its upper armatures, as previously described, a through talking circuit may be established over the plug P and jack J to the distant station by way of conductors 1 and 2 of trunk A. A circuit is also provided over sleeve conductor 44, which lights the supervisory lamp 49, which may be traced from ground at the local line D, cut-off relay 5-4, over sleeve contacts of jack J of local line D and plug P of cord B, conductor 44, contact 45, conductor 50, armature and con tact of relay 51, through said lamp, conductor 52, contact 53 of key K to grounded battery. When the subscriber removes the telephone from its hook at local line D supervisory relay 51 will be energized by the following circuit: from grounded battery, winding of said relay, conductor 56, lower right winding of repeating coil R, contact 43, lower armature of relay 41, armature of relay 37, ring contacts of plug P and J over the local line, in a well understood manner, and return by way of tip side of the line D and cord B, upper armature of relay 37, armature and contact 42 of relay 41, upper right winding of repeating coil R to ground. Talking battery is furnished by this circuit, and, upon the energization of relay 51, the circuit for lamp 49 is broken.

In response to a call from-local line D. indicated by the lighting of lamp 57 plug P or plug P of local cord 0 may be associated therewith. In case the call is local, the plug which is not used will provide for the local interconnection with another local line through cord C. In case, however, upon the association of either of the previously mentioned local plugs with the local line, the operator finds that the call is for a toll connection, she will at once disconnect the plug of the local cord C, and substitute therefor plug P of the toll cord B, as the local cord C is not adaptedfor use in connection with toll lines, as will later appear. Upon the connection of the plug P with jack J of local line D, and plug P with jack J of trunk line A, the operation will be similar to that described previously with relation to an incoming call over the trunk line for connection with a local line.

If, in response to a call incoming over the toll line A, the lamp 5 be lighted, as previously described, and should plug P instead of plug P be associated with the jack J the path for current may be traced from ground, relay 6, conductor 55, upper armature of relay 36, tip contacts of plug P and jack J, talking conductor 1, conductor 8, upper contact and armature of relay 9, conductor 10, winding of relays 11 and 12 to grounded battery. The relay 1.2 is so de signed that it will not operate because of the high resistance of relay 6, as formerly pointed out, but relay 11 is energized and a circuit is closed from grounded battery, left hand armature and contact of relay 12, left hand winding ofrelay 13, contact and armature of relay 11, conductor 16, conductor 2,

ring contacts'of jack J and plug P upper armature and contact 36 of relay 37, conductor 38, upper winding of relay 39 to ground. Relay 39 is energized by'this cir- I lay being thus energized, closes its armaarmature of relay 9, conductor 10, through presently appear.

tures, thereby breaking contacts 42 and 43 and establishing a direct talking connection to conductors 21 and 22. The energization of relay 13 in thetoll line also provides a current path from ground, contact and armature of relay 12, right hand winding of relay 13, including its armature and contact, sleeve contacts of jack J andplug P sleeve conductor 44 of cord B, through the lower winding of relay 39 to grounded battery. Relay 46 is also energized by current passing over conductor 47, through the winding of relay 16 to grounded battery. Relay 46 upon operating will attract its armature and provide a circuit thereover from ground, conductor 48, winding of relay 37 to grounded battery. Relay 37 will be thereby energized and attract its armatures, and, as the armatu'res of relay 41 have been attracted as previously explained, a through toll connection may be provided over talking conductors 21 and 22, upon the association of the plug P with any of the toll lines, such as is indicated at A, at the private branch exchange. 2

Should a local cord, such as is illustrated at C, and which is intended only for local interconnections, be associated with the toll line A, no connections can be completed thereover because of reasons which will Should the plug P be inadvertently inserted in the jack 'J, in response to an incoming call over the trunk A, and indicated by the lighting of lamp 5, such operation would cause relays 11 and 12 of toll line A to be energized by the follow ing circuit: from ground at repeating coil R over the tip conductor of local cord C, tip contacts of plug P and jack J, talking conductor 1, conductor 8, upper contact and windings of relays 11 and '12 to grounded battery. Belay 12 will be energized by the circuit just traced, since the resistance of the repeating coil R is sufliciently low to permit said relay to operate. One of the functions of relay 12 is to prevent the closing of the talking conductors of the toll line -A'in case a local cord, such as C, is plugged into the toll line with a talking battery of higher potential than the normal signaling battery, as is sometimes done for transmission reasons. In this case, relay 13,

when connected to the line by relay 11, would operate on the differences of the two battery potentials if it were not for the fact that relay 12 had operated. To prevent the momentary operation of relay 13 in this condition, the left hand back contacts of relay 12 are adjusted to break before the contacts of relay 11 close. Upon the operation of relay 12 both of its armatures are attracted, and thus it will be seen that relay 13 does not function because it depends for its operation upon the armatures of relay 12 remaining retracted. Therefore, the lamp 5 will continue to glow, and, as it is obvious that no talking circuit is established, the operator will not be able to complete a toll connection over the local 'cord Noting these conditions she will readily substitute the toll cord B and complete the connection.

If the plug P of local cord 0 be associated with jack J of the toll line, the same conditions would prevail as previously outlined in connection with plug P Current will pass from ground at the repeating coil R over the tip conductor and tip contacts of plug P and ack J through the windings of relays 11 and 12, energizing the latter relay and dissociating its armature from their contacts, thus depriving relay 13 of circuit-connections which are necessary for its operation. I

From the foregoingfit will be apparent that a private branch exchange operator may be provided with equipment including local cord circuits and toll cord circuits, the former adapted for use only in connection with local calls, and the latter adapted for use with through toll connections or connections from toll lines to local lines. Furthermore, it will be obvious that by means of this invention no toll connections can be completed by local cords, the toll line circuits and apparatus responding only when associated with toll cords, so that by this arrangement full advantage of improved transmission over said toll cords is obtained.

While the arrangements of this invention have been illustratedas embodied in certain specific arrangements, which have been deemed desirable, it will be understood that they are capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a telephone system, a toll trunk, talking conductors for said trunk, a cord circuit for answering calls incoming over said trunk, a second cord circuit for completing local connections, a marginal relay associated with the toll trunk, a second relay, means under the control of said second relay for controlling the' establishment of a talking connection over said talking conductors, means whereby upon the association of the first named cord with the toll trunk said marginal relay remains unact-uated thereby permitting the operation of said second relay, and whereby when said second cord is associated with the trunk the marginal relay is actuated and the operation of said second relay is defeated.

2. In a telephone system, a toll trunk, talking conductors for said trunk, a cord circuit for answering calls incoming over said trunk, a second cord circuit for completing local connections, a marginal relay associated with the toll trunk, a nonmarginal relay in series therewith, a third relay under the joint control of the marginal and non-marginal relays, means governed by said third relay for controlling the establishment or" a talking connection over said talking conductors, means whereby upon the association of the first named cord with the toll trunk said non-marginal relay is actuated and said marginal relay remains unactuated thereby permitting the operation of said third relay, under the control of said non-marginal relay and Whereby when said second cord is associated with the trunk the marginal relay is actuated and the operation of said third relay is defeated.

3. In a telephone system, a toll trunk, talking conductors for said trunk, a cord circuit for answering calls incoming over said trunk, a relay associated with the trunk, and means including a sleeve relay associated with said trunk and operable upon the actuation of said first mentioned relay to establish a talking connection through said cord circuit.

4. In a telephone system, a toll trunk, talking conductors for said trunk, a cord circuit for answering calls incoming over said trunk, a marginal relay associated with the trunk, a second relay in series therewith, a third relay under the joint control of said marginal and second relays for establishing a talking connection over said trunk, and means including a sleeve relay associated with said cord and operable upon the actuation of said third relay to establish a talking connection over said cord.

5. In a telephone system, a toll trunk, talking conductors for said trunk, a cord circuit adapted through one of its terminals for handling calls incoming or outgoing over said trunk, a sleeve relay associated with said cord circuit, a second relay controlled thereby, a switching relay associated with the sleeve and ring conductors of said cord, a source of battery supply current, and means including said second relay and a relay operable upon the energization of the switching relay whereby a talking circuit is established and said source of battery supply current is disconnected from the cord upon the association of said cord circuit with a toll line.

6, In a telephone system, a toll trunk, a local trunk, talking conductors for said trunks, a cord circuit adapted through one of its terminals for handling calls incoming or outgoing over either of said trunks, a sleeve relay associated with said cord circuit, a second relay controlled thereby, a switching relay associated with the sleeve and ring conductors of said cord, a high impedance bridge, means including said second relay, and a relay operable upon the energization of the switching rela whereby a talking circuit is establishe and the high impedance bridge is connected therewith upon the association of said cord circuit with said toll line, a source of battery supply current, and means controlled by said second relay whereby said high impedance bridge is eliminated when the cord circuit is associated with said local trunk and said source of battery supply current is associated with the cord.

In testimony whereof we have signed our names to this specification this 21st day of February, 1919.

OSCAR M. ARNOLD. JOHN F. TOOMEY. 

